*Actions covered:Acquisition (Buy): Purchase of sharesDisposal (Sell): Sale of sharesPledge: Shares being used by promoters as collateral for loans. Usually a negative signal.Revoke: When shares are released from a pledge. Usually a positive signal. Invoke: When pledged shares are invoked by companies/banks who have provided the collateral, which may result in acquisition of stake in the company. Usually a negative signal.